Safety drive



D@ z8 1926. 1 1,611,963 y H. S. VALENTINE SAFETY DRIVE l Filed August 28, 1923 Patented Dec. 28, 1926.

srA'rEs HERBERT S. VALENTINE, OF PHILADELIHIA, PENNSYLVANIA, ASSIGNOR 'I AMERI- CAN ENGINEERING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- TION OF PENNSYLVANIA.

SAFETY DRIVE.

Application filed August 28, 1923. Serial No. 659,778. l

One object of this invention is to provide a relatively simple, conveniently adjustable automatic safety device particularly designed to be included in and i'orm part of the train of gears on a hoist, for automatae cally disconnecting the source of power from the load in the event of the latter exceeding a predetermined amount, and more particularly, it is desired to provide a safety device which shall be so placed in the gear train as to permit of relatively light working pressures to the square inch between the coacting 'friction surfaces, that when these slip or move relatively to each other, there shall not be that sudden drop in power transn mitting capacity which occurs under similar conditions when the pressure between the coacting parts is relatively great.

rihe invention i'urther contemplates the insertion of a safety device in a gear train at that point where the gears have a maximum speed, under which conditions it is possible to operate said device with relatively low pressure between its coacting friction suri'faces, thus giving a practically continuous constant torque when said surfaces slip or move relatively to each other.

rlhese objects and other advantageous ends, I attain as hereinafter set forth, reference being had to the accompanying draw-V ings in which,

Fig, 1 is a sectional plan illustrating my invention as applied to a well known form ot hoist; and,

Fig. 2 is an enlarged vertical section further illustrating my invention.

l'n the above drawings, 1 represents an electric motor connected through a gear train S12-39 to the drum 2 oit a hoist, and in accordance with my invention I insert my safely device in said gear train immediately adjacent said electric motor where the gears operate at a. maximum speed. Vlith this idea in view, the pinion 32 on the armature shait ot the motor meshes with the gear 33 and my safety device is included between this latter gear and the nent succeeding pinion 3l ot the gear train. For this purpose, I provide a shaft 5 having one end supported in suitable anti-triction bearings 6 carried by the fixed structure and supported 'indirectly as hereafter explained in a bearing provided by a second fixed structure 8 adjacent the structure 'i'. Said shaft has keyed to it a plate 9 having a flat tace extending yparallel with and immediately adjacent the corresponding Iflat tace formed on one side of the gear 83. Said gear is mounted to run loosely on the shaft 5 and its second tace is likewise flat, having adjacent it the iat tace ot' a second plate 10. This latter plate is keyed or otherwise rigidly fixed to an elongated sleeve 11 splined to the shaft 5 so as `to be rotated therewith while free to move longitudinally thereon to a limited extent. The pinion 34 is fixed to this sleeve, in the presentcase integrally, and said sleeve eX- tends through a shouldered bushing 12 mounted in the fixed structure 8 so as to be tree to rotate therein, A flanged ring 13 is mounted on the shaft 5 so as to bear against the end of the sleeve 11 and between this and a second flanged ring 11i is mounted a relatively heavy coiled spring 15 which with said rings is confined within the outer end ot the bushing 12. The adjacent extremity o'li the shaft 5 is threaded tor an adjustable nut 16 bearing againstthe outer one o'r the rings 1d and capable ot being locked in any given position by pin or lrey 17 passing through the shaft end. rlhis adjustable nut and the parts immediately adjacent thereto are inclosed by a cap 18 threaded on the sleeve 12.

Between the adjacent fiat tace ot the gear 33 and the two plates 9 and l() are mounted rings or annular plates 24e and 25 of suitable friction material such as parchmentized libre, brake lining or the like, so that when the nut 1G is set up to compress the spring 15, the latter acts through the sleeve 11, gear 84, and plate 10 to frictionally press the latter toward the gear 33 and the gear 33 toward the plate 9 with a definite and relatively light pressure per square inch. Under these conditions, when power is applied to the gear 33, it is normally transmitted to the pinion 34, the various parts being de signed to run in oil, tor which purpose the two plates 9 and 10 are formed with lubricating channels 20., 21, 22 to insure the tree delivery of lubricant to the rings 2li and 25.

When connected in the gear train of a hoist immediately adjacent the driving motor 1 as shown in Fig. 1, said motor when in operation will turn the drum and raise the load attached to the cable wound thereon. The pressure between the coacting friction surfaces in the above described device is lUD lll

relatively loiv, and this is permissible by reason of the fact that saiddevice is connected in the gear train at a point thereof immediately adjacent the driving motor Where the speed of the power transmitting elements is high. As a consequence, when relative motion occurs between the `gear 33 and its coaeting` friction surfaces by reason of an abnormal load on the hoist, there is no sudden and excessive drop of power transmitting ycapacity such as would oecur if slippage occurred when the pressure per square ,inch between the cQacting-CT friction surfaces was relatively high, llflien the device operates therefore the torque is practically continuous and constant. l

I claim l, In combination,y a high speed shaft; a low speed shaf" and means intei-.conneetine` the same comprising a clutch shaft; a sleeve splined thereto; gear fixed to said sleeve and operatively associated vith said low speed shaft; a second gear loosely mounted onthe clutch shaft and operatively associated with. said high speed shaft; two plates mounted to turn with the clutch shaft and Vpositioned to frictionally cooperate With opposite sides of the second gear; and a spring operative through the sleeve to force the plates into gripping' engagement vvith the second `near, whereby the powcrjtrans! mittingf capacity of said high speed shaft is substantially unaffected by slippage of said plates.

In combination, a high speed shaft; a low speed shaft; and moans for interconnesting the same comprising' a clutch shaft; a sleeve splined to said clutch shaft and including an integral gear operatively associated vfith said low speed shaft; a second gear loosely mounted on the clutch shaft and operatively associated with the high speed shaft; tivo friction plates respectively cooperating with opposite sides of said second gear and so mounted to turn with said first-mentioned gear; and a spring;- operative on the sleeve for maintaininfr said plates and the second gear in frictional engagenientE whereby :the power transmitting capacity of said high speed shaft is substantially independent of relative movement between said plates and said second gear..

in combination, a high speed shaft; a low speed shaft, and mear-is for linterconnecting` the same comprising` a clutch shaft; plate mounted on said clutch shaft; a gear loose on the shaft and frictionally engaging said plate, said gear being operatively associated ,with said high speed shaft.; ka sleeve splined to said clutch shaft; a second plate lit-ed ilo the sleeve in yposition to frictionally engage the sei-:ond face lof said gear; a second gear on said sleeve, said second rearl being' operatively associated With said low speed sha g and a spring operative on the sleeve to force said plates and first gear into frictional eng` gement; whereby the power transinitting` capacity of said vhigh speed shaft is substantially independent of relative movement between said plates and said firstnientioned freer.

e. In combination. a high speed shaft; a low speed shaft; and means for operatively associating the same comp isine a clutch shaft; a casing providing' a journal for said clutch shaft, the latter projecting outside of said casing; a sleeve splined to said clutch shaft; a gear loose on the clutch shaft and operatively associated With said high speed shaft; two plates mounted to frictionally engage opposite faces of said gear, one of said plates being operatively associated with said sleeve; a gear on the sleeve operatively assoelated with said low speed shaft; an adjustable member on the portion of the'clutch shaft outs' e, ofthe casing; and al spring` connected .tween said adjustable member and the adjacent end of the sleeve, the speed of said first-mentioned shaft heine' such that the pressure of said plates on said irstaneir tioncd gear relatively low, whereby the power transmitting capacity of said high speed 'shaft is substantially independent of relative movement between said plates and said first-mentioned gear.

HERBERT S. VALENTINE.v 

